1. Field of the Invention
The present invention relates to a circuit arrangement for testing parts of a digital time-division multiplex telecommunication switching center, particularly a telephone switching center comprising a check word generator for generating check words that are transmitted in defined time channels to the appertaining parts of the switching center and, after a mirroring, are transmitted back to the sending location where they are monitored for coincidence with the transmitted check word by a comparison with a receiving circuit.
2. Description of the Prior Art
Tests that are carried out according to the above-mentioned principle can differ due to the part of the switching center for whose monitoring they serve but, on the other hand, can also differ in terms of their objectives. A test whose objective is to check the switching-oriented procedures of the switching center at a switching center in which the line groups are formed with a group switching matrix network between which a connection is possible via a redundant, central switching matrix network can therefore be directed to a group switching matrix network or to the one or to the other part of the redundant, central switching matrix network. Such tests serving the purpose of checking the switching-oriented procedures are respectively implemented after the set-up procedures for a defined connection have been concluded and before the through-connection is then undertaken.
In addition to tests having this objective that must be implementable in time channels for the through-connection of calls, tests also come into consideration that are directed to defined assemblies within the switching center, for example multiplexers or interfaces, and for whose implementation a specific, fixed time channel is reserved. Another type of testing is provided in cases of a division of the switching center into active and redundant line groups is being provided in the form of continuous channel tests. They are then permanently executed at the respectively redundant line groups in a defined time channel that is not required for the through-connection of a call.
Due to such differences of the tests in terms of area of coverage and in terms of objective, there is an interest to be able to sequence individual test in parallel with one another. Heretofore, a separate test receiver was provided for each of the different test loops, the monitoring of the check word transmitted back on the test loop for coincidence with a transmitted check word having been undertaken on the basis thereof. Such a solution, of course, represents a considerable hardware expense for a greater plurality of tests to be executed in parallel.